Polyamide composite filaments having an improved latent crimpability

ABSTRACT

Polyamide composite filaments having an improved latent crimpability wherein two different fiber-forming polyamide components are mutually bonded and eccentrically disposed over the cross section of the filament, one of the components being a homopolyamide selected from the group consisting of polycaproamide and hexamethylene adipamide and the other of the components being a copolyamide which contains in its main molecular chain at least one polymeric structural unit derived from equimolar amounts of a dibasic acid and a diamine, at least one of said dibasic acid and said diamine having not more than four carbon atoms, the average number of moles of amide-linkages in the main molecular chain of said copolyamide being 5 to 15 per kilogram of polymer.

United States Patent Ando et al. I

[54] POLYAMIDE COMPOSITE FILAMENTS HAVING AN IMPROVED LATENTCRIMPABILITY [72] Inventors: Satoshi Ando; Yusaku Tanaka, both of Osaka;Sadao Onuma, Kobe; lhimimaro Ogata, Osaka, all of Japan [731 Assignees:SNIA UISCOSA Societa Nazionale Industria Applieazioni Viscosa S.p.A.,Milan, Italy; Kanegafuchi Boseld Kabushiki Kaisha, Tokyo, Japan [22]Filed: July 17, 1969 [21 A'ppl.No.: 842,736

Related US. Application Data [63] Continuation-impart of Ser. No.625,985, Mar. 27,

1967,abandone I [52] U.S.Cl ..161/173, 161/177 [51] Int. Cl ..D02g 3/04[58] FieldofSearch ..161/173,175,177;264/l71, 264/DIG. 26

[56] References Cited UNITED STATES PATENTS 2,130,523 9/1938 Carothers..260/78 [151 3,642,568 51 Feb. 15,1972

3,118,011 1/1964 Breen ..264/DIG. 26 3,515,703 6/1970 Yeda eta]..161/173 X FOREIGN PATENTS OR APPLICATIONS 40/25,l73 11/1965 Japan..264/D1G. 26

Primary Examiner-Robert F. Burnett Assistant Examiner-Linda C. KoeckertAttorneyStevens, Davis, Miller & Mosher ABSTRACT Polyamide compositefilaments having an improved latent crimpability wherein two differentfiber-forming polyamide components are mutually bonded and eccentricallydisposed over the cross section of the filament, one of the componentsbeing a homopolyamide selected from the group consisting ofpolycaproamide and hexamethylene adipamide and the other of thecomponents being a copolyamide which contains in its main molecularchain at least one polymeric structural unit derived from equimolaramounts of a dibasic acid and a diamine, at least one of said dibasicacid and said diamine having not more than four carbon atoms, theaverage number of moles of amide-linkages in the main molecular chain ofsaid copolyamide being 5 to 15 per kilogram of polymer.

1 Claim, No Drawings 7 physical and chemical properties the filament,polyamides are used as said two components to be bonded.

Hitherto it has been well known that composite filaments in which twofiber-forming polymer components having different suchas heatshrinkability or swellability are bonded eccentrically throughout theentire length of the filaments, develop spiral three-dimensional crimpsupon exposure to heat or a swelling agent under relaxed conditions.

As the above two components, homopolyamides are used advantageously incombination with copolyamides because of their high spinnability,because they show similar melting points and melt-viscosities as well assatisfactory mutual adhering properties. For instance, whenpolycaproamide is used as one component, it has been a most generalmethod to use as the other component a copolymer obtained bypolycondensing e-caprolactam with a salt of diamine with dibasic acideach having six or more carbon atoms. However, such homopolyamides andcopolyamides have relatively similar chemical and physical structures,so that crimpability latent in the obtained composite filament is poorand desired bulkiness and covering power of the crimped compositefilament cannot be brought about.

An object of the present invention is to provide polyamide compositefilaments having an excellent latent crimpability.

Another object of the present invention is to provide crimped compositefilaments having high bulkiness and covering power.

A further object of the present invention is to provide compositefilaments economically by using raw materials of low cost.

The present invention consists in polyamide composite filaments havingan improved latent crimpability, which are obtained by simultaneouslyspinning together through the same spinneret orifice two differentfiber-forming synthetic linear polymer components to form unitaryfilaments in which said components are eccentrically disposed towardseach other in distinct zones with adjoining surfaces being in intimateadhering contact with each other, each of said components extendingthroughout the length of said filaments, one of said components being ahomopolyarnide selected from polycaproamide and polyhexamethyleneadipamide, the other component being a copolyamide which contains in itsmain molecular chain at least one polymeric structural unit derived fromequimolar amounts of a dibasic acid and a diamine, at least one of saiddibasic acid and said diamine having not more than four carbon atoms,the average number of moles of amide-linkages in the main molecularchain of said copolyamide being 5 to per kilogram of polymer.

It has been well known that the crimpability of composite filaments isbased on the difference in shrinkability between the two componentsconstituting the filament, and the inventors have investigated therelation between the shrinkability and the chemical structure ofpolyamides to find that the shrinkability of polyamides is highlyinfluenced by the number of amide-linkages in the main molecular chain,and the present invention has been achieved.

That is to say, it has been found that the shrinkability of polyamidefilaments depends upon the concentration of amide-linkages with respectto methylene radicals in the polymeric structural unit and upon thenumber of moles of amide-linkages in the main molecular chain of thepolymer, and that the higher they are, the greater the shrinkability.Based on this, the crimpability of polyamide composite filaments hasbeen successfully increased by introducing into the of a dibasic acidand a acid and said diamine having not more than four carbon atoms,whereby the concentra- Thus polyamides containing a polymeric structuralunit derived from a dibasic acid and a diamine, at least one of saiddibasic acid and said diamine having not more than four carmolecularchain have never so far been used as filament-forming materials becausethey have drawbacks in melt-spinnability and in strength, elongation andYoungs Modulus as monofilaments but a useful application of thesepolyamides for composite filaments has been developed by the presentinvention.

The term average number of moles of amide-linkages contained in the mainmolecular chain of polyamide used herein means average number of molesof amide-linkage per kilogram of polymer. in the case that w-lactams orw-aminoacids are used as the raw materials for the polyamide, theaverage number can be calculated as that l mole of amide-linkage iscontained in 1 mole of polymeric structural unit, while when a nylonsalt of diamine and dibasic acid is employed, it may be calculated asthat 1 mole of polymeric structural unit contains 2 moles ofamide-linkage. For instance, polycaproamide andpolyhexamethyleneadipamide which consists respectively of polymericstructural units HN(CH CO and HN(CH CO have 8.9 moles of amide-linkageper kilogram of polymer on an average. Furthermore, in the case of acopolyamide which comprises two or more polymeric structural units, theaverage number of amide-linkages to be contained in homopolyamidecomposed of each of the above polymeric structural units is calculatedand then the average number of amide-linkages contained in thecopolyamide is estimated from the above each calculated value accordingto the amount of each polymeric structural unit in the copolyamide. Forexample, a copolyamide consisting of percent by weight of polycaproamideand 20 percent by weight of polyhexamethylene sebacamide which has beenhitherto used as a component of conventional polyamide compositefilaments has 8.5 moles of amide-linkage per kilogram of polymer on anaverage.

The average number of moles of amide-linkages contained in the mainmolecular chain of copolyamide employed for the present invention isfrom 5 to l5 and preferably from 7 to 13 per kilogram of polymer. If theaverage number of moles of amide-linkages is less than 5, theshrinkability decreases to such an extent that a satisfactorycrimpability of the composite filament can hardly be obtained, whilewhen the average number of moles of amide-linkages is more than 15,hydroscopicity and swellability are so excessive in the obtainedfilament that the physical properties of the filament are loweredconsiderably, and these filaments are not suitable for a practical use.

Moreover, the copolyamides hitherto used generally, which containstructural units derived from dibasic acids and diamines, at least oneof said dibasic acids and said diamines having more than five carbonatoms, in the main molecular chain, do not give high shrinkability, eventhough the average number of moles of amide-linkages falls within theabovementioned range, so that it is essential that at least one of saiddibasic acid and said diamine to constitute the structural units of thecopolyamide has not more than four carbon atoms and that the averagenumber of moles of amide-linkages therein is within the above-mentionedrange in order to achieve the object of the present invention.

copolyamides to be employed in this invention which contain polymericstructural units derived from diamines or dibasic acids, at least one ofsaid dibasic acids and said diamines having not more than four carbonatoms, in the main molecular chain, can be produced by copolymerizing aconventional polyamide-forming monomer with a salt of one or morediamines, such as, ethylenediamine, propylenediamine,tetramethylenediamine with conventional nylon-forming dibasic acids, orsalts of one or more dibasic acids, such as, malonic acid, succinic acidwith conventional nylon-forming diamines. As valuable members of thisclass may be mentioned poly(carproamide/ethylene adipamide),poly(caproamide/ethylene sebacamide), poly(caproamide/ethyleneterephthalamide), poly(caproamide/ethylene isophthalamide),poly(caproamide/tetramethylene adipamide),poly(caproamide/tetramethylene isophthalamide), poly(caproamide/ethylenesuccinamide), poly(caproamide/hexamethylene malonamide),poly(caproamide/nonamethylene succinamide), poly(hexamethyleneadipamide/ethylene adipamide), poly(hexamethylene adipamide/ethyleneterephthalamide), poly(hexamethylene adipa mide/tetramethylenemalonamide), poly(hexamethylene adipamide/propylene isophthalamide),poly(hexamethylene sebacamide/ethylene isophthalamide) andpoly(hexamethylene sebacamide/hexamethylene succinamide).

Thus, according to the invention, composite filaments having an improvedcrimpability, which have never so far been obtained, may be provided,because there is a considerable difference in the shrinkability betweenthe two components constituting the composite filaments. Moreover,diamines or dibasic acids having not more than four carbon atoms can beobtained in a low cost as compared with the other raw materials forpolyamides, so that the cost of production can be lowered.

in the present invention, the conjugate ratio of the two components canbe varied suitably, and moreover the bonding form of two components maybe either in a side-byside relation or an eccentric sheath and corerelation along the entire length ofthe filament.

The cross section of the composite filament obtained according to theinvention may be noncircular as well as circular.

The composite filament obtained according to the invention can be usedfor continuous filament or staple fiber. Moreover, the compositefilament obtained according to the invention can be improved remarkablyin its crimpability and covering property as compared with that obtainedby the conventional methods, so that it can be used widely for variousfabrics, knitted goods, piled articles, etc.

Moreover. crimps of the composite filament obtained according to thepresent invention can be developed either before or after producingfinished goods.

The following examples are given in illustration of the invention andare not intended as limitations thereof.

The crimpability shown in the following examples was determined asfollows: that is, bundles consisting of 40 filaments cut into 30 cm.length were hung with various weights, and then in such a state dippedin hot water at 95 C. for 15 minutes to develop crimps, after which theywere dried in air, and then percents of shrinkage for the initial lengthwere measured. Next, loads calculated per denier and percents ofshrinkage were plotted and the load at 50 percent ofshrinkage wasmentioned as halfload value.

EXAMPLE 1 A mixture of 90 parts (by weight) of e-caprolactam with lparts (by weight) of a salt of ethylenediamine with adipic acid washeated at 250 C. for 8 hours under nitrogen gas atmosphere to effectpolycondensation. The copolyamide thus obtained (average number of molesof amide-linkages per kilogram of polymer was 9.1) and polycaproamidewere conjugate spun at a conjugate ratio of 1:1 (by weight ratio) in aside-by-side relation to obtain a composite filament in which twocomponents were arranged in side-by-side type relationship along theentire length of the filament. The obtained composite filament was drawnto 4.2 times its original length at room temperature to obtain a deniercomposite filament.

The crimpability of above-mentioned composite filament was determined asabove resulting in that its percent of shrinkage under no load was 90.2percent, and its halfload value was 1.2 mg./d.

In order to compare the above-mentioned composite filament with aconventional filament, conjugate spinning was carried out under the samecondition as described above using a salt of hexamethylenediamine andadipic acid (in this case the average number of moles of amide-linkagesof this copolyamide was 8.8) instead of the salt of ethylenediamine andadipic acid. In determining the crimpability of the resulting compositefilament, the percent of shrinkage under no load was only 71 percent,and the half load value was only 0.15 mg./d.

EXAMPLE 2 A mixture of 92 pans (by weight) of caprolactam with 8 parts(by weight) of a salt of ethylenediamine and isophthalic acid was heatedat 250 C. for 8 hours under a nitrogen gas atmosphere to effectpolycondensation. The obtained copolyamide (average number of moles ofamide-linkages per kilogram of polymer was 9.0) and polycaproamide wereconjugate spun at 250 C. at a conjugate ratio of 1:1 (by weight ratio)in a side-by-side type relationship, and the spun filament was drawn to4.4 times its original length to obtain a 13 denier composite filament.The obtained filament was measured with respect to its crimpabilityresulting in that percent of shrinkage under no load was 89.8 percentand half load value was 1.06 mg./d.

The same procedure was repeated except that a salt ofundecamethylenediamine with isophthalic acid (in this case, the averagenumber of moles of amide-linkages was 8.7 per kilogram of polymer) wasused instead of the above-mentioned salt of ethylenediamine withisophthalic acid to obtain a composite filament, the percent ofshrinkage of which was only 79.3 percent under no load and half loadvalue was only 0.34 mg./d.

EXAMPLE 3 A mixture of 40 parts (by weight) of a salt ofhexamethylenediamine with adipic acid, 60 parts (by weight) ofa salt oftetramethylenediamine with sebacic acid and 50 parts (by weight) ofwater was introduced into an autoclave and prepolymerized at atemperature of 250 C. for 2 hours under a pressure of 25 kg./cm. afterwhich the resulting mass was heated and polycondensed under nitrogen gasatmosphere at 280 C. for 5 hours to obtain a copolyamide (average numberof moles of amide-linkages of this polymer was 8.3). Then the obtainedcopolymer and polyhexamethylene adipamide were conjugate spun at aconjugate ratio of 1:1 (by weight ratio) in a side-by-side typerelationship at 290 C., and then the extruded filament was drawn to 3.8times its original length at room temperature to obtain an 18 deniercomposite filament.

The obtained composite filament had an excellent crimpability, and thepercent of shrinkage under no load was 93 percent and the halfload valuewas 1.8 mg./d.

The same procedure was repeated except that a salt ofhexamethylenediamine with sebacic acid (in this case, the average numberof moles of amide-linkages in the copolyamide was 7.8 per kilogram ofpolymer) was used instead of the salt of tetramethylenediamine withsebacic acid to obtain a composite filament, the percent of shrinkage ofwhich was only 73 percent under no load and the halfload value was only0.62 mg./d.

EXAMPLE 4 A mixture of 88 parts (by weight) of caprolactam with 12 parts(by weight) of a salt of mixed diamines consisting of ethylenediamineand tetramethylenediamine in a mole ratio of 1:1 with terephthalic acidwas heated an polycondensed under nitrogen gas atmosphere at atemperature of 250 C. for 8 hours to obtain a copolyamide (averagenumber of moles of amide-linkages per kilogram of polymer was 9.0). Thenthe obtained copolyamide and polycaproamide were conjugate spun at aconjugate ratio of 1:1 (by weight ratio) in a side-byside typerelationship at a temperature of 250 C., after which the resultingfilament was drawn to 4.4 times its original length to obtain a deniercomposite filament. The composite filament obtained had an excellentcrimpability, and the percent of shrinkage under no load was 92 percent,and the half load value was 1.25 mg./d.

The same procedure was repeated except that nonamethylenediamine andundecamethylenediamine (in this case the average number of moles ofamide-linkages per kilogram of polymer was 8.6) was used instead of theabove-mentioned ethylenediamine and tetramethylenediamine to obtain acomposite filament, which was a very inferior filament, and the percentof shrinkage under no load was 75 percent, and the halfload value was0.15 mg./d.

EXAMPLE 5 V A mixture of parts (by weight) of caprolactam, 80 parts (byweight) of a salt of hexamethylenediamine with malonic acid and 50 parts(by weight) of water was introduced into an autoclave and prepolymerizedat a'temperature of 250 C. for 2 hours under a pressure of kg./cm. afterwhich the result ing mass was heated and polycondensed at atmosphericpressure under nitrogen gas atmosphere at a temperature of 260 C. for 5hours to obtain a copolyamide (average number of moles of amide-linkagesper kilogram of polymer was 9.0). Then the obtained copolyamide andpolycaproamide were conjugate spun at a conjugate ratio of 1:1 (byweight ratio) in a side-by-side type relationship at a temperature of260 C., and then the resulting filament was drawn to 4.0 times itsoriginal length to obtain a l5 denier composite filament.

The obtained composite filament had an excellent crimpability, and thepercent of shrinkage under no load was 95 percent and the halfload valuewas 1.92 mg./d.

The same procedure was repeated except that a salt ofhexamethylenediamine with sebacic acid (in this case, the

' average number of moles of amide-linkages per kilogram of polymer was7.4) was used instead of the above-mentioned salt ofhexamethylenediamine with malonic acid to produce a composite filament,the percent of shrinkage of which was only 81 percent under no load andthe half load value was only 0.55 mg./d.

We claim:

1. Polyamide composite filaments having an improved latent crimpabilitymanufactured by simultaneously spinning together through a commonspinneret orifice two different fiber-forming synthetic linear polymercomponents to form unitary filaments, in which said components areeccentrically disposed towards each other in distinct zones withadjoining surfaces being in intimate adhering contact with each other,each of said components extending throughout the length of saidfilaments,

one of said components being a homopolyamide selected from the groupconsisting of polycaproamide and hexamethylene-adipamide, and

the other component being a copolyamide which contains in its mainmolecular chain at least one polymeric structural unit derived fromequimolar amounts of a dibasic acid and a diamine, at least one of saiddibasic acid and said diamine having not more than four carbon atoms,which is selected from the class consisting of poly(caproamide/ethyleneadipamide), poly(caproamide/ethylene sebacamide),poly(caproamide/ethylene terephthalamide), poly(caproamide/ethyleneisophthalamide), poly(caproamide/tetramethylene adipamide),poly(caproamide/tetramethylene isophthalamide), poly(caproamide/ethylenesuccinamide), poly(caproamide/hexamethylene malonamide),poly(caproamide/nonamethylene succinamide), poly(hexamethyleneadipamide/ethylene adipamide), poly(hexamethylene adipamlde/ethyleneterephthalamide), poly(hexamethylene adipamide/tetramethylenemalonamide), poly(hexamethylene adipamide/propylene isophthalamide),poly(hexamethylene sebacamide/ethylene isophthalamide) andpoly(hexamethylene sebacamide/hexamethylene succinamide), the averagenumber of moles of amide-linkages in the main molecular chain of saidcopolyamide being 5 to 15 per kilogram of polymer.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. v 3$112,568 Dated February 15, 1972 Inventofls) Satoshi Ando et al.

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

The Assignee '5 name should be changed from "SNIA UISCOSA" to SNIAVISCOSA Signed and sealed this 18th day of June 197E.

(SEAL) Attest:

EDWARD M.FLETGI-]IER,JR. c. MARSHALL DANN Attesting Officer Commissionerof Patents USCOMM-DC 60876-1 69 FORM PC4050 (10-69) I i u.s. cov'smmnnPRINTING omc: no o-au-su.

